In general, electronic devices have various functions and perform complex functions. The electronic devices may be connected to communicate with each other. At this time, the electronic devices may be connected to each other wirelessly or through a wire. That is, the electronic devices may be connected to each other through a wireless communication network for intercommunication. The electronic devices may perform a call through the wireless communication network. To this end, the electronic devices may generate a public security key and utilize it to establish a secure call session. Thus, the electronic devices may exchange calls or messages securely through the wireless communication network.
However, the communication between the electronic devices remains vulnerable to external attacks. That is, the security key of the electronic devices may be exposed to the external attack and altered. Accordingly, the content of a call or message of the electronic devices may be exposed. For example, an eavesdropper (e.g., sometimes referred to as a “man in the middle”) may control the security key to listen to the content of a call between the electronic devices. In addition, messages of the electronic devices may be exposed by external attack. As a result, messages between the electronic devices may be blocked, or the content of the message may be changed.